Salts of bile acids act as detergents to solubilize and, consequently, aid in the digestion of, dietary fats. Bile acids are derived from cholesterol. Following digestion, bile acids can be passively absorbed in the jejunum or reabsorbed by active transport in the ileum. Bile acids which are not reabsorbed are deconjugated and dehydroxylated by bacterial action in the distal ileum and large intestine.
Reabsorption of bile acids from the intestine conserves lipoprotein cholesterol in the bloodstream. Conversely, the blood cholesterol level can be reduced by hindering reabsorption of bile acids.
One method of reducing the amount of bile acids that are reabsorbed is oral administration of compounds that sequester the bile acids and cannot themselves be absorbed. The sequestered bile acids consequently are excreted. Serum cholesterol is then employed to produce more bile acids, thereby lowering the serum cholesterol level of the patient.